1. Field of the Invention
This invention relates in general to carriers, and more particularly to a laminated damping device for a common carrier.
2. Description of Related Art
In some conventional disk files, the data storage disk is mounted horizontally for rotation about a vertical axis, and is mounted on a main body or chassis. The disk head, which may be a read-only head or a read-and-write head, is movably mounted on the main body of the disk file, for movement over the disk to desired tracks. Although in some circumstances the disk file may be permanently and rigidly fixed in the frame or other equipment, it often occurs that the disk file must be mounted so as to be easily removable from a supporting frame. For example, file server products put a number of hard disk drives (HDD) into a single cabinet to reach storage requirements.
In other arrangements the disk file may be mounted vertically for a rotation about a horizontal axis. In general in this specification, it is to be appreciated that the description of a disk file applies equally well to a disk file position in a vertical plane for rotation about a horizontal axis, or indeed another configurations where appropriate.
A problem which arises in operation of disk files occurs at the end of the seek movement of the actuator across the disk. The rotational energy created by an HDD actuator is high enough to move its own casting and create servo errors if it is not restrained, which also results in write inhibits, soft errors, and slow response time. This may be generally characterized as self-induced problems. In recent years the actuators on disk files have generally changed from linear to rotary operation, the read/write heads being moved in an arch across the disk, about a vertical axis (for a horizontal disk) position on the main body of the disk file, outside the perimeter of the disk.
The vibrations arising from acceleration and deceleration of such a rotary actuator produce rotary oscillation of the main body of the disk file in a horizontal plane. The axis acceleration and deceleration of the actuator, containing the read/write heads, particularly on high performance disk files, results in an equivalent reaction to the main body of the disk file. In addition, the hard disk drive creates vibration energy when the disk stack is out of balance. These vibration energies may be transmitted to adjacent drives. This transmitted vibration energy may result in write inhibits, soft errors, and slow response from the HDDs. This may generally be characterized as vibration transmission problems.
As more tracks are written per inch on HDD products, the severity of the problems will increase. Thus, future HDD products will require system cabinets and carriers which take these issues more into account.
The system cabinet construction and file mounting (or carrier) have a significant impact on the magnitude of these two problems. The vibration transmission problems can be resolved with a very soft, or isolation mount system. The self-induced problems can be solved with a very stiff or hard mount. Thus, trying to solve one of the problems may counteract attempts to solve the other problem, or even aggravate the other problem. To resolve both problems, the mounting system and cabinet must have a combination of stiffness and damping that restrain the file enough to minimize self-induced problems, yet do not transmit significant vibration energy from adjacent files.
Further, when the hard disk drives have mounting problems, the excessive write inhibits that are posted may result in a preventative action to replace the drive, when in reality the drive is fine, it is just a mounting problem.
It can be seen that there is a need for a device for a common carrier to absorb vibration transmissions from a disk drive file to other co-located disk drive files and to minimize self-induced vibration problems.
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a damping device for a common carrier.
The present invention solves the above-described problems by providing a damping device with a top element, a bottom element, and a viscoelastic element between the top and bottom elements. The damping device exerts significant shear displacement across the viscoelastic element upon deflecting.
In a preferred embodiment the damping device has first and second ends and an intermediate portion between the first and second ends. The damping device has a generally longitudinal extension with an elevation in the direction of the top element in the intermediate portion. The elevation has a substantially triangular V-shape when the damping device is unloaded.
A system in accordance with the principles of the present invention includes a system cabinet, a plurality of carriers mounted in the system cabinet for receiving hard disk drives, and a plurality of damping devices according to the invention mounted between the carriers and the system cabinet.
A method of making a damping device includes laminating a viscoelastic element between a top element and a bottom element and providing the damping device with a shape by which the damping device exerts significant shear displacement across the viscoelastic element upon deflecting.
Other embodiments of a system in accordance with the principles of the invention may include alternative or optional additional aspects.
An advantage of a damping device according to the invention is that it overcomes both problems with self-induced vibration and problems with vibrations transmitted from other carriers in the system cabinet. A further advantage is that in using a system according to the invention, the vibration problems related to the mounting have been overcome, whereby functioning drives should no longer be replaced unnecessarily.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.